Traumatic brain injury (“TBI”) is a common and devastating condition. Of the 1.4 million civilians who sustain a TBI each year in the United States, approximately 1.1 million are treated and released from an emergency department, 235,000 are hospitalized, and 50,000 die. Traumatic brain injury is the number one cause of pediatric death and disability. Long-term disability can range from functional changes affecting thinking, language and learning, to physical, emotional and behavioral changes. Traumatic brain injury can cause epilepsy and increase the risk for conditions such as Alzheimer's disease, Parkinson's disease, and other brain disorders that become more prevalent with age.
Traumatic brain injury (TBI) results in an increase in intracranial pressure (“ICP”). Elevated ICP reduces cerebral perfusion pressure (“CPP”), which lowers cerebral blood flow (“CBF”). As the injured brain becomes increasingly more ischemic, brain swelling ensues, causing more ischemia, further brain injury, herniation and oftentimes death. TBI outcome depends on the severity of primary brain injury and the effectiveness of preventing or limiting secondary brain injury.
Evidence-based guidelines for the management of severe traumatic brain injury have been developed, yet a wide spectrum of methods still characterizes most monitoring and treatment strategies. The most widely used, current method for intracranial pressure monitoring involves placement of an intracranial pressure monitoring device. This is an invasive procedure that involves cutting the scalp and drilling a hole through the patient's cranium, so that a pressure transducer can be inserted in or on top of the brain. Newer, non-invasive methods for intracranial pressure and cerebral perfusion monitoring have been described; however, these methods are still considered experimental and none are in clinical practice. These non-invasive, intracranial pressure monitoring methods include: transcranial Doppler ultrasonography; transcranial optical radiation, such as near-infrared spectroscopy; ophthalmodynamometry; arterial pulse phase lag; and ocular coherence tomography.
Further, existing techniques for measuring ICP often will not provide sufficient findings to inform the selection of an appropriate therapeutic strategy for the TBI. Fluid resuscitation strategies are poorly understood, difficult to study and variably practiced. Inadequate resuscitation poses the risk of hypotension and end organ damage. Conversely, aggressive fluid resuscitation may dislodge clots from vascular injuries, resulting in further blood loss, hemodilution and death. How to best proceed when one is dealing with a multiply-injured patient who has a traumatic brain injury and exsanguinating hemorrhage can be especially difficult. Under resuscitation can harm the already injured brain, whereas overresuscitation can reinitiate intracranial bleeding and exacerbate brain swelling, leading to brain herniation, permanent neurological injury and oftentimes death.
Accordingly, new techniques for non-invasive assessment, monitoring, and treatment of TBI, and elevated ICP generally, are urgently needed.